Image Sensor Black Reference Isolation Against Lateral Light
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Solution Overview
Problem
Image sensors face challenges in accurately calibrating electrical signals due to non-optically generated signals such as leakage and dark currents, which are not effectively canceled out by existing methods.
Innovation Solution
Incorporating a ring-shaped light blocking structure around black reference image sensors to prevent lateral light from entering, using a metal shielding layer to block light and prevent optical cross-talk, and forming a doped region adjacent to the light blocking structure to reduce electrical leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If black reference image sensors are used to generate non-optically generated signals, then calibration of electrical signals can be performed, but lateral light may enter and contaminate the reference signals, reducing measurement precision
Solution Approach 1:
A light blocking structure is introduced as an intermediary element between the pixel array region and the black reference image sensor region. This structure laterally surrounds the pixel array region and blocks light from reaching the black reference image sensors, thereby eliminating lateral light interference while preserving the calibration function.
Solution Approach 2:
The image sensor device is segmented into distinct functional regions: a pixel array region for light detection, a black reference image sensor region for calibration, and a light blocking structure that separates these regions. This spatial segmentation prevents cross-contamination of light signals between regions.
2Measurement precision
If no light blocking structure is used, then device complexity is reduced, but optical cross-talk occurs between pixel array and reference sensors, worsening measurement precision
Solution Approach 1:
The light blocking structure serves as a minimal yet effective intermediary that prevents optical cross-talk. By positioning this structure to laterally surround the pixel array region, it provides the necessary isolation between functional regions without requiring complex multi-layer shielding or intricate designs.
3Reliability
If doped region is formed adjacent to light blocking structure, then electrical leakage is reduced, but manufacturing process complexity increases
Solution Approach 1:
The doped region is merged with the light blocking structure in the fabrication process. The doped region is formed adjacent to the light blocking structure during the same manufacturing sequence, combining two functional elements (light blocking and electrical isolation) into a coordinated structure that reduces electrical leakage paths without requiring entirely separate fabrication processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively isolates black reference image sensors from light, allowing for accurate generation of non-optically generated signals, thereby improving the calibration of electrical signals and reducing unwanted noise.
Implementation Method 1
Incorporating a ring-shaped light blocking structure around black reference image sensors to prevent lateral light from entering, using a metal shielding layer to block light
Implementation Method 2
forming a doped region adjacent to the light blocking structure to reduce electrical leakage
Data Source
AI summary
A method for fabricating an image sensor device is provided. The method includes forming a plurality of photosensitive pixels in a substrate; depositing a dielectric layer over the substrate; etching the dielectric layer, resulting in a first trench in the dielectric layer and laterally surrounding the photosensitive pixels; and forming a light blocking structure in the first trench, such that the light blocking structure laterally surrounds the photosensitive pixels.